Many simple holding devices have been designed throughout history, perhaps starting with a primitive hook fashioned from a bone of some particular animal. Then, probably the art advanced to the preparation of the more intricate tooling devices assembled from chosen bones and seashells to perform particular tooling operations.
Development of the many metals encouraged the design and use of many strong and necessary holding and linking devices, such as chains, snap hooks of many kinds, and various linking devices using swivel components.
I found some of these more sophisticated linking devices while searching the prior art on behalf of my own invention.
Some of these are shown in the following U.S. patents:
______________________________________ 184,709 Haines Nov. 28, 1876 340,838 Walters et al April 27, 1886 345,086 Stahl July 6, 1886 544,483 Eckert Aug. 13, 1895 D33,410 Covert Oct. 23, 1900 1,514,772 Kinnear Nov. 11, 1924 D152,135 Becker Dec. 21, 1948 D157,122 Blake et al Feb. 7, 1950 3,912,318 Engh Oct. 14,1975 4,061,388 Wilkinson Dec. 6, 1977 D281,222 Faidide Nov. 5, 1985 D283,673 Berg May 6, 1986 ______________________________________